Create field_model_ifc_timestamp.py

src/django-ifc/fields/model/field_model_ifc_timestamp.py

@@ -0,0 +1,109 @@
+# -*- coding: utf-8 -*-
+
+
+# =============================================================================
+# Docstring
+# =============================================================================
+
+"""
+Provides IFC Timestamp Model Field Class
+===================================
+
+
+https://standards.buildingsmart.org/IFC/RELEASE/IFC2x3/TC1/HTML/ifcmeasureresource/lexical/ifctimestamp.htm
+
+"""  # noqa E501
+
+
+# =============================================================================
+# Import
+# =============================================================================
+
+# Import | Standard Library
+import datetime
+
+# Import | Libraries
+from django.db import models
+from django.utils.timezone import make_aware, get_default_timezone
+from django.core.exceptions import ValidationError
+from django.utils.translation import gettext_lazy as _
+
+# Import | Local Modules
+
+
+# =============================================================================
+# Variables
+# =============================================================================
+
+__all__ = ["IfcTimestampField", ]
+
+
+# =============================================================================
+# Classes
+# =============================================================================
+
+class IfcTimestampField(models.TextField):
+    """
+    IFC Timestamp Model Field Class
+    ===============================
+
+    Custom Django field for storing IfcTimeStamp, which is the number of
+    seconds since 00:00:00 Coordinated Universal Time (UTC), Thursday,
+    1 January 1970.
+
+    This field stores the time as an integer but interacts with Python's
+    datetime objects, automatically handling conversion between these for
+    ease of use within Django.
+
+    """
+
+    def from_db_value(self, value, expression, connection):
+        """
+        Convert an integer from the database to a datetime.datetime object.
+        """
+        if value is None:
+            return value
+        try:
+            return make_aware(
+                datetime.datetime.utcfromtimestamp(value),
+                get_default_timezone()
+            )
+        # Handle overflow error which can happen with large timestamps
+        except OverflowError:
+            raise ValidationError(
+                _("Timestamp value is out of range for datetime.")
+            )
+
+    def to_python(self, value):
+        """
+        Convert the value to a datetime.datetime object.
+        """
+        if isinstance(value, datetime.datetime):
+            return value
+        if value is None:
+            return value
+        try:
+            return make_aware(
+                datetime.datetime.utcfromtimestamp(int(value)),
+                get_default_timezone()
+            )
+        except (ValueError, OverflowError):
+            raise ValidationError(_("Invalid timestamp value."))
+
+    def get_prep_value(self, value):
+        """
+        Convert the datetime.datetime object to an integer timestamp before
+        saving to the database.
+        """
+        if isinstance(value, datetime.datetime):
+            return int(value.timestamp())
+        return value
+
+    def value_to_string(self, obj):
+        """
+        Convert the datetime value to a string for serialization.
+        """
+        value = self.value_from_object(obj)
+        return str(
+            int(value.timestamp())
+        ) if isinstance(value, datetime.datetime) else ''